Try to get a ford V-8 or V-10 that is 2001 or later. They had addressed the spark issues by then. Otherwise it is several hundred to fix a spark plug that blows out.
The price seems a bit high. As a comparison, last year I bought a 2001 or 2002 (I would have to check the title, my memory isn't what it used to be) E350 V-10, XLT, 15 passenger with 80k in perfect condition with some aftermarket stuff (tow brake controller, better sound system, alarm, etc.) from the original owner in California with all maintenance records for $5000.00 (well actually $5200 but I sold the tires and wheels for $200 when I added my custom wheels/tires). Also don't be afraid to negotiate and have cash ready. The seller of my van was asking $6500.00
Be patient and find the right van, it took me 3 months. With me, a vehicle talks to me when it is the right one....... I guess I'm the "Car Whisperer" .... LOL
Gregg